Curcumin activates autophagy and attenuates oxidative damage in EA.hy926 cells via the Akt/mTOR pathway

Curcumin, which is the effective component of turmeric (Curcuma longa), has previously been shown to exert potent antioxidant, antitumor and anti-inflammatory activities in vitro and in vivo. However, the mechanism underlying the protective effects of curcumin against oxidative damage in endothelial cells remains unclear. The present study aimed to examine the effects of curcumin on hydrogen peroxide (H2O2)-induced apoptosis and autophagy in EA.hy926 cells, and to determine the underlying molecular mechanism. Cultured EA.hy926 cells were treated with curcumin (5-20 mu mol/l) 4 h prior to and for 4 h during exposure to H2O2 (200 mu mol/l). Oxidative stress resulted in a significant increase in the rate of cell apoptosis, which was accompanied by an increase in the expression levels of caspase-3 and B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), and a decrease in the expression levels of Bcl-2. Treatment with curcumin (5 or 20 mu mol/l) significantly inhibited apoptosis, and reversed the alterations in caspase-3, Bcl-2 and Bax expression. Furthermore, curcumin induced autophagy and microtubule-associated protein 1A/1B-light chain 3-II expression, and suppressed the phosphorylation of Akt and mammalian target of rapamycin (mTOR). These results indicated that curcumin may protect cells against oxidative stress-induced damage through inhibiting apoptosis and inducing autophagy via the Akt/mTOR pathway.